New marking technologies based on thermochromic inks are becoming increasingly popular. Such marking technologies use thermochromic ink based labels. Thermochromic ink based labels work by permanently changing state according to the amount of energy deposited over a given area. The technology provides an analog or grayscale printing capability where pixels are developed after exposure to some minimum threshold amount of energy deposited per unit area. Complex systems are required for directing near sufficient energy onto a moving media.
In prior art embodiments, fixed speed media paths are required, or assumed, in order to ensure the correct amount of energy is deposited in the correct portion of the label for the thermochromic ink to be developed. However, fixed speeds are rarely practical and, in some cases, not possible in real world applications. Prior art methods and systems are not equipped to image media on a process line at speeds ranging from a standstill up to 2 meters per second, or faster. Retrofitting existing process lines to operate at a fixed speed is expensive, and in some cases, impossible.
For processing lines with variable speeds, prior art marking techniques that assume fixed media speed provide poor quality imaging. In addition, small variations in an otherwise constant media speed, caused by process line errors or other such events, can result in missed markings or failure to mark the desired area at all. Poor quality markings and missed markings are expensive to detect and correct, and can result in significant cost.
Accordingly, a need exists for print systems equipped to track media speed and adjust the energy levels of the marking engine to provide a consistent uniform energy at the media surface.